Evaporator and refrigeration cycle apparatus including the same

ABSTRACT

An evaporator includes: fins disposed at a predetermined interval in a fin thickness direction; heat transfer tubes extending through the fins in the fin thickness direction; and a first heat exchange section in which, when the heat transfer tubes are viewed in the fin thickness direction, a center of distribution of the heat transfer tubes in an airflow direction is disposed on a leeward side of a center of the fins in the airflow direction. The evaporator is disposed in a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed.

TECHNICAL FIELD

The present disclosure relates to an evaporator of a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed.

BACKGROUND

As an evaporator of a refrigeration cycle apparatus, there is an evaporator in a form in which a plurality of heat transfer tubes are unevenly distributed more on either one of the windward side and the leeward side of the center of a heat transfer fin. For example, the evaporator described in PTL 1 (WO2017/183180) is a stack-type heat exchanger in which elongated holes each having a longitudinal diameter extending in the width direction of a fin are provided at a predetermined interval in a direction orthogonal to the width direction and the thickness direction of the fin and in which a flat pipe is inserted into each of the elongated holes.

SUMMARY

An evaporator according to one or more embodiments is an evaporator of a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed, the evaporator including a plurality of fins and a plurality of heat transfer tubes. The plurality of fins are arranged at a predetermined interval in a plate thickness direction (a fin direction). The plurality of heat transfer tubes extend through the plurality of fins in the plate thickness direction. In the evaporator, a first heat exchange section is formed. In the first heat exchange section, when the plurality of heat transfer tubes are viewed as a heat-transfer-tube group in the plate thickness direction of the fins, a distribution center of the heat-transfer-tube group in an airflow direction is positioned on the leeward side of the center of the fins in the airflow direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an air conditioning apparatus as a refrigeration apparatus according to one or more embodiments of the present disclosure.

FIG. 2 is a schematic front view of an indoor heat exchanger.

FIG. 3 is an external perspective view of an outdoor heat exchanger.

FIG. 4 is a P-H diagram of a non-azeotropic refrigerant mixture.

FIG. 5A is a perspective view of a first heat exchange section of an outdoor heat exchanger according to first embodiments.

FIG. 5B is a perspective view of a second heat exchange section of the outdoor heat exchanger according to the first embodiments.

FIG. 6A is a schematic perspective view of an outdoor heat exchanger that uses both the first heat exchange section and the second heat exchange section.

FIG. 6B is a schematic perspective view of a different outdoor heat exchanger that uses both the first heat exchange section and the second heat exchange section.

FIG. 7A is a perspective view of a first heat exchange section of an outdoor heat exchanger according to second embodiments.

FIG. 7B is a perspective view of a second heat exchange section of the outdoor heat exchanger according to the second embodiments.

FIG. 7C is a perspective view of a third heat exchange section of an outdoor heat exchanger according to a modification of the second embodiments.

FIG. 8A is a perspective view of a first heat exchange section of an outdoor heat exchanger according to third embodiments.

FIG. 8B is a perspective view of a second heat exchange section of the outdoor heat exchanger according to the third embodiments.

FIG. 8C is a perspective view of a third heat exchange section of an outdoor heat exchanger according to a modification of the third embodiments.

DETAILED DESCRIPTION First Embodiments

(1) Configuration of Air Conditioning Apparatus 1

FIG. 1 is a schematic diagram of an air conditioning apparatus 1 according to one or more embodiments of the present disclosure. In FIG. 1, the air conditioning apparatus 1 is a refrigeration apparatus that performs cooling operation and heating operation by a vapor compression refrigeration cycle.

A refrigerant circuit 10 of the air conditioning apparatus 1 is constituted by an outdoor unit 2 and an indoor unit 4 that are connected to each other via a liquid-refrigerant connection pipe 5 and a gas-refrigerant connection pipe 6.

A refrigerant enclosed in the refrigerant circuit 10 is a non-azeotropic refrigerant mixture. The non-azeotropic refrigerant mixture includes any of a HFC (hydrofluorocarbon) refrigerant, a HFO (hydrofluoroolefin) refrigerant, CF3I (trifluoroiodomethane), and a natural refrigerant.

(1-1) Indoor Unit 4

The indoor unit 4 is installed indoors and constitutes part of the refrigerant circuit 10. The indoor unit 4 includes an indoor heat exchanger 41, an indoor fan 42, and an indoor-side control unit 44.

(1-1-1) Indoor Heat Exchanger 41

The indoor heat exchanger 41 functions as an evaporator for the refrigerant during cooling operation and cools indoor air. In addition, the indoor heat exchanger 41 functions as a radiator for the refrigerant during heating operation and heats indoor air. The refrigerant inlet side of the indoor heat exchanger 41 during cooling operation is connected to the liquid-refrigerant connection pipe 5, and the refrigerant outlet side thereof is connected to the gas-refrigerant connection pipe 6.

FIG. 2 is a front view of the indoor heat exchanger 41. In FIG. 2, the indoor heat exchanger 41 is a cross-fin-type heat exchanger. The indoor heat exchanger has a heat transfer fin 412 and a heat transfer tube 411.

The heat transfer fin 412 is a thin aluminum flat plate. The heat transfer fin 412 has a plurality of through holes. The heat transfer tube 411 has a straight tube 411 a inserted into the through holes of the heat transfer fin 412, and U-shaped tubes 411 b and 411 c that couple end portions of mutually adjacent straight tubes 411 a to each other.

The straight tube 411 a is in close contact with the heat transfer fin 412 by being subjected to tube expansion processing after inserted into the through holes of the heat transfer fin 412. The straight tube 411 a and the first U-shaped tube 411 b are formed integrally with each other. The second U-shaped tube 411 c is coupled to an end portion of the straight tube 411 a by welding, brazing, or the like after the straight tube 411 a is inserted into the through holes of the heat transfer fin 412 and subjected to tube expansion processing.

(1-1-2) Indoor Fan 42

The indoor fan 42 takes indoor air into the indoor unit 4, causes the indoor air to exchange heat with the refrigerant in the indoor heat exchanger 41, and then supplies the air to the inside of a room. As the indoor fan 42, a centrifugal fan, a multi-blade fan, or the like is employed. The indoor fan 42 is driven by an indoor fan motor 43.

(1-1-3) Indoor-Side Control Unit 44

The indoor-side control unit 44 controls operation of each portion that constitutes the indoor unit 4. The indoor-side control unit 44 has a microcomputer and a memory that are for controlling the indoor unit 4.

The indoor-side control unit 44 transmits and receives a control signal and the like to and from a remote controller (not illustrated). In addition, the indoor-side control unit 44 transmits and receives a control signal and the like to and from an outdoor-side control unit 38 of the outdoor unit 2 via a transmission line 8 a.

(1-2) Outdoor Unit 2

The outdoor unit 2 is installed outdoors and constitutes part of the refrigerant circuit 10. The outdoor unit 2 includes a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 26, a liquid-side shutoff valve 27, and a gas-side shutoff valve 28.

(1-2-1) Compressor 21

The compressor 21 is a device that compresses a low-pressure refrigerant of the refrigeration cycle. The compressor 21 drives and rotates a positive-displacement compression element (not illustrated) of a rotary type, a scroll type, or the like by a compressor motor 21 a.

A suction pipe 31 is connected to the suction side of the compressor 21, and a discharge pipe 32 is connected to the discharge side thereof. The suction pipe 31 is a refrigerant pipe that connects the suction side of the compressor 21 and the four-way switching valve 22 to each other. The discharge pipe 32 is a refrigerant pipe that connects the discharge side of the compressor 21 and the four-way switching valve 22 to each other.

An accumulator 29 is connected to the suction pipe 31. The accumulator 29 separates a flowed-in refrigerant into a liquid refrigerant and a gas refrigerant and causes only the gas refrigerant to flow to the suction side of the compressor 21.

(1-2-2) Four-Way Switching Valve 22

The four-way switching valve 22 switches the direction of the flow of the refrigerant in the refrigerant circuit 10. During cooling operation, the four-way switching valve 22 causes the outdoor heat exchanger 23 to function as a radiator for the refrigerant and causes the indoor heat exchanger 41 to function as an evaporator for the refrigerant.

During cooling operation, the four-way switching valve 22 connects the discharge pipe 32 of the compressor 21 and a first gas refrigerant pipe 33 of the outdoor heat exchanger 23 to each other and connects the suction pipe 31 of the compressor 21 and a second gas refrigerant pipe 34 to each other (refer to the solid lines of the four-way switching valve 22 in FIG. 1).

During heating operation, the four-way switching valve 22 is switched to a heating cycle state in which the outdoor heat exchanger 23 functions as an evaporator for the refrigerant and in which the indoor heat exchanger 41 functions as a radiator for the refrigerant.

During heating operation, the four-way switching valve 22 connects the discharge pipe 32 of the compressor 21 and the second gas refrigerant pipe 34 to each other and connects the suction pipe 31 of the compressor 21 and the first gas refrigerant pipe 33 of the outdoor heat exchanger 23 to each other (refer to the broken lines of the four-way switching valve 22 in FIG. 1).

Here, the first gas refrigerant pipe 33 is a refrigerant pipe that connects the four-way switching valve 22 and the refrigerant inlet of the outdoor heat exchanger 23 during cooling operation to each other. The second gas refrigerant pipe 34 is a refrigerant pipe that connects the four-way switching valve 22 and the gas-side shutoff valve 28 to each other.

(1-2-3) Outdoor Heat Exchanger 23

The outdoor heat exchanger 23 functions as a radiator for the refrigerant during cooling operation. In addition, the outdoor heat exchanger 23 functions as an evaporator for the refrigerant during heating operation. One end of a liquid refrigerant pipe 35 is connected to the refrigerant outlet of the outdoor heat exchanger 23 during cooling operation. The other end of the liquid refrigerant pipe 35 is connected to the expansion valve 26.

The outdoor heat exchanger 23 will be described in detail in the section “(3) Detailed Structure of Outdoor Heat Exchanger 23”.

(1-2-4) Expansion Valve 26

The expansion valve 26 is an electric expansion valve. During cooling operation, the expansion valve 26 decompresses a high-pressure refrigerant that is sent from the outdoor heat exchanger 23 to a low pressure. During heating operation, the expansion valve 26 decompresses a high-pressure refrigerant that is sent from the indoor heat exchanger 41 to a low pressure.

(1-2-5) Liquid-Side Shutoff Valve 27 and Gas-Side Shutoff Valve 28

The liquid-side shutoff valve 27 is connected to the liquid-refrigerant connection pipe 5. The gas-side shutoff valve 28 is connected the gas-refrigerant connection pipe 6. The liquid-side shutoff valve 27 is positioned downstream the expansion valve 26 in a refrigerant circulation direction during cooling operation. The gas-side shutoff valve 28 is positioned upstream the four-way switching valve 22 in a refrigerant circulation direction during cooling operation.

(1-2-6) Outdoor Fan

The outdoor unit 2 includes an outdoor fan 36. The outdoor fan 36 takes outdoor air into the outdoor unit 2, causes the outdoor air to exchange heat with the refrigerant in the outdoor heat exchanger 23, and then discharges the air to the outside. As the outdoor fan 36, a propeller fan or the like is employed. The outdoor fan 36 is driven by an outdoor-fan motor 37.

(1-2-7) Outdoor-Side Control Unit 38

The outdoor-side control unit 38 controls operation of each portion that constitutes the outdoor unit 2. The outdoor-side control unit 38 has a microcomputer and a memory that are for controlling the outdoor unit 2.

The outdoor-side control unit 38 transmits and receives a control signal and the like to and from the indoor-side control unit 44 of the indoor unit 4 via the transmission line 8 a.

(1-3) Refrigerant Connection Pipes 5 and 6

The connection pipes 5 and 6 are refrigerant pipes that are constructed at a local site during installation of the air conditioning apparatus 1 in an installation location at a building or the like. As each of the connection pipes 5 and 6, a pipe having an appropriate length and an appropriate diameter is employed in accordance with installation conditions such as an installation location, a combination of the outdoor unit 2 and the indoor unit 4, and the like.

(2) Basic Operation of Air Conditioning Apparatus

Next, a basic operation of the air conditioning apparatus 1 will be described with reference to FIG. 1. The air conditioning apparatus 1 is capable of performing cooling operation and heating operation as basic operation.

(2-1) Cooling Operation

During cooling operation, the four-way switching valve 22 is switched to a cooling cycle state (the state indicated by the solid lines in FIG. 1). In the refrigerant circuit 10, a low-pressure gas refrigerant of the refrigeration cycle is sucked by the compressor 21 and discharged after compressed.

The high-pressure gas refrigerant discharged from the compressor 21 is sent to the outdoor heat exchanger 23 via the four-way switching valve 22.

In the outdoor heat exchanger 23 that functions as a radiator, the high-pressure gas refrigerant sent to the outdoor heat exchanger 23 radiates heat by exchanging heat with outdoor air supplied from the outdoor fan 36, and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is sent to the expansion valve 26.

The high-pressure liquid refrigerant sent to the expansion valve 26 is decompressed to a low pressure of the refrigeration cycle by the expansion valve 26 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant decompressed in the expansion valve 26 is sent to the indoor heat exchanger 41 via the liquid-side shutoff valve 27 and the liquid-refrigerant connection pipe 5.

The low-pressure gas-liquid two-phase refrigerant sent to the indoor heat exchanger 41 evaporates in the indoor heat exchanger 41 by exchanging heat with indoor air supplied from the indoor fan 42. Consequently, the indoor air is cooled. Then, the cooled air is supplied to the inside of a room, thereby cooling the inside of the room.

The low-pressure gas refrigerant that has evaporated in the indoor heat exchanger 41 is sucked again by the compressor 21 via the gas-refrigerant connection pipe 6, the gas-side shutoff valve 28, and the four-way switching valve 22.

(2-2) Heating Operation

During heating operation, the four-way switching valve 22 is switched to the heating cycle state (the state indicated by the broken lines in FIG. 1). In the refrigerant circuit 10, a low-pressure gas refrigerant of the refrigeration cycle is sucked by the compressor 21 and discharged after compressed.

The high-pressure gas refrigerant discharged from the compressor 21 is sent to the indoor heat exchanger 41 via the four-way switching valve 22, the gas-side shutoff valve 28, and the gas-refrigerant connection pipe 6.

The high-pressure gas refrigerant sent to the indoor heat exchanger 41 radiates heat in the indoor heat exchanger 41 by exchanging heat with indoor air supplied from the indoor fan 42, and becomes a high-pressure liquid refrigerant. Consequently, the indoor air is heated. Then, the heated air is supplied to the inside of a room, thereby heating the inside of the room.

The high-pressure liquid refrigerant that has radiated heat in the indoor heat exchanger 41 is sent to the expansion valve 26 via the liquid-refrigerant connection pipe 5 and the liquid-side shutoff valve 27.

The high-pressure liquid refrigerant sent to the expansion valve 26 is decompressed to a low pressure of the refrigeration cycle by the expansion valve 26 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant decompressed in the expansion valve 26 is sent to the outdoor heat exchanger 23.

The low-pressure gas-liquid two-phase refrigerant sent to the outdoor heat exchanger 23 evaporates in the outdoor heat exchanger 23 by exchanging heat with outdoor air supplied from the outdoor fan 36, and becomes a low-pressure gas refrigerant.

The low-pressure refrigerant that has evaporated in the outdoor heat exchanger 23 is sucked again by the compressor 21 through the four-way switching valve 22.

(3) Detailed Description of Outdoor Heat Exchanger 23

(3-1) Structure

FIG. 3 is an external perspective view of the outdoor heat exchanger 23. In FIG. 3, the outdoor heat exchanger 23 is a stack-type heat exchanger. The outdoor heat exchanger 23 includes a plurality of flat pipes 231 and a plurality of heat transfer fins 232.

(3-1-1) Flat Pipes 231

Each flat pipe 231 is a multi-hole pipe. The flat pipe 231 is formed of aluminum or an aluminum alloy and has a flat portion 231 a that serves as a heat transfer surface, and a plurality of internal flow paths 231 b in which the refrigerant flows.

The flat pipes 231 are arrayed in a plurality of stages to be stacked with a gap (ventilation space) therebetween in a state in which respective flat portions 231 a are directed upward/downward.

(3-1-2) Heat Transfer Fins 232

Each heat transfer fin 232 is a fin made of aluminum or an aluminum alloy. The heat transfer fin 232 is disposed in a ventilation space between the flat pipes 231 that are vertically adjacent to each other and is in contact with the flat portions 231 a of the flat pipes 231.

The heat transfer fin 232 has cutouts 232 c (refer to FIG. 5A and FIG. 5B) into which the flat pipes 231 are inserted. After the flat pipes 231 are inserted into the cutouts 232 c of the heat transfer fins 232, the heat transfer fins 232 and the flat portions 231 a of the flat pipes 231 are joined to each other by brazing or the like.

(3-1-3) Headers 233 a and 233 b

The headers 233 a and 233 b are coupled to both ends of the flat pipes 231 arrayed in the plurality of stages in the up-down direction. The headers 233 a and 233 b have a function of supporting the flat pipes 231, a function of guiding the refrigerant to the internal flow paths of the flat pipes 231, and a function of gathering the refrigerant that has flowed out from the internal flow paths.

When the outdoor heat exchanger 23 functions as an evaporator for the refrigerant, the refrigerant flows into the first header 233 a. The refrigerant that has flowed into the first header 233 a is distributed to the internal flow paths of the flat pipes 231 of the stages substantially evenly and flows toward the second header 233 b. The refrigerant that flows in the internal flow paths of the flat pipes 231 of the stages absorbs heat via the heat transfer fins 232 from an air flow that flows in the ventilation spaces. The refrigerant that has flowed in the internal flow paths of the flat pipes 231 of the stages gathers at the second header 233 b and flows out from the second header 233 b.

When the outdoor heat exchanger 23 functions as a radiator for the refrigerant, the refrigerant flows into the second header 233 b. The refrigerant that has flowed into the second header 233 b is distributed to the internal flow paths of the flat pipes 231 of the stages substantially evenly and flows toward the first header 233 a. The refrigerant that flows in the internal flow paths of the flat pipes 231 of the stages radiates heat via the heat transfer fins 232 into an air flow that flows in the ventilation spaces. The refrigerant that has flowed in the internal flow paths of the flat pipes 231 of the stages gathers at the first header 233 a and flows out from the first header 233 a.

(3-2) Suppression of Frost

FIG. 4 is a P-H diagram of a non-azeotropic refrigerant mixture. In FIG. 4, the refrigerant temperature increases toward the evaporator outlet. Since the composition of the non-azeotropic refrigerant mixture is different between a liquid phase and a gas phase, a “temperature gradient” in which an evaporation start temperature and an evaporation end temperature in the evaporator are different is present. Due to the temperature gradient, the temperature at the inlet easily decreases in the evaporator, which easily causes frost during heating operation.

FIG. 5A is a perspective view of a first heat exchange section 23 a of the outdoor heat exchanger 23 according to one or more embodiments. In FIG. 5A, the opening side of the cutouts 232 c is positioned on the leeward side in the airflow direction in the first heat exchange section 23 a.

FIG. 5B is a perspective view of a second heat exchange section 23 b of the outdoor heat exchanger 23 according to one or more embodiments. In FIG. 5B, the opening side of the cutouts 232 c is positioned on the windward side in the airflow direction.

Since the openings of the cutouts 232 c are positioned on the windward side in the airflow direction in the second heat exchange section 23 b illustrated in FIG. 5B, a difference between an air temperature and a heat-exchanger surface temperature is large, and thus has a feature of improving heat exchange performance but easily causing frost.

Meanwhile, since the openings of the cutouts 232 c are positioned on the leeward side in the airflow direction in the first heat exchange section 23 a illustrated in FIG. 5A, a difference between an air temperature and a heat-exchanger surface temperature is small compared with the second heat exchange section 23 b. Frost is thus suppressed.

Therefore, in one or more embodiments, the first heat exchange section 23 a is formed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator.

(3-3) Improvement of Heat Exchange Performance

As described above, compared with the second heat exchange section 23 b, a difference between an air temperature and a heat-exchanger surface temperature is small in the first heat exchange section 23 a. The heat exchange performance is thus degraded. Therefore, constituting the entirety of the outdoor heat exchanger 23 by the first heat exchange section 23 a may not be preferable for performance.

Thus, in one or more embodiments, both the first heat exchange section 23 a and the second heat exchange section 23 b are used to improve heat exchange performance while suppressing frost.

FIG. 6A is a schematic perspective view of the outdoor heat exchanger 23 that uses both the first heat exchange section 23 a and the second heat exchange section 23 b. FIG. 6B is a schematic perspective view of a different outdoor heat exchanger 23′ that uses both a first heat exchange section 23 a′ and a second heat exchange section 23 b′.

In FIG. 6A, when the outdoor heat exchanger 23 functions as an evaporator for the refrigerant, the refrigerant that has flowed into the first header 233 a is distributed to the internal flow paths 231 b of the flat pipes 231 of the stages substantially evenly and flows toward the second header 233 b. The temperature of the non-azeotropic refrigerant mixture at the evaporator inlet easily decreases, which easily causes frost. Therefore, a certain section from the first header 233 a toward the second header 233 b is constituted by the first heat exchange section 23 a to suppress frost.

Meanwhile, the temperature of the non-azeotropic refrigerant mixture increases toward the evaporator outlet. Thus, to improve heat exchange performance, a part between the first heat exchange section 23 a and the second header 233 b is constituted by the second heat exchange section 23 b.

It is possible by thus disposing the first heat exchange section 23 a on the evaporator inlet side and the second heat exchange section 23 b on the evaporator outlet side to improve heat exchange performance while suppressing frost.

In FIG. 6B, when the outdoor heat exchanger 23′ functions as an evaporator for the refrigerant, the refrigerant that has flowed into the lower stage of the first header 233 a′ is distributed to internal flow paths 231 b′ of the flat pipes 231 of the stages of the lower stage substantially evenly and flows toward the second header 233 b′.

The refrigerant that has reached the lower stage of the second header 233 b′ gathers temporarily and flows into the upper stage of the second header 233 b′ via a curved pipe 234. Thereafter, the refrigerant is distributed to the internal flow paths 231 b of the flat pipes 231 of the stages of the upper stage substantially evenly and flows toward the second header 233 b′.

The temperature of the non-azeotropic refrigerant mixture at the evaporator inlet easily decreases, which easily causes frost. Therefore, a section from the lower stage of the first header 233 a′ toward the lower stage of the second header 233 b′ is constituted by the first heat exchange section 23 a′ to suppress frost.

Meanwhile, the temperature of the non-azeotropic refrigerant mixture increases toward the evaporator outlet. Thus, to improve heat exchange performance, a section from the upper stage of the first header 233 b′ toward the upper stage of the first header 233 a′ is constituted by the second heat exchange section 23 b′.

It is possible by thus disposing the first heat exchange section 23 a′ on the evaporator inlet side and the second heat exchange section 23 b′ on the evaporator outlet side to improve heat exchange performance while suppressing frost.

(4) Features

(4-1)

In the first heat exchange section 23 a of the outdoor heat exchanger 23, the opening side of the cutouts 232 c of the heat transfer fins 232 is positioned on the leeward side in the airflow direction. By disposing the first heat exchange section 23 a on the side of the inlet for the non-azeotropic refrigerant mixture, it is possible to improve frost proof performance (capacity of suppressing frost) when the outdoor heat exchanger 23 functions as an evaporator.

(4-2)

In addition, by disposing the first heat exchange section 23 a on the side of the inlet for the non-azeotropic refrigerant mixture and disposing the second heat exchange section 23 b, in which the openings of the cutouts 232 c are positioned on the windward side in the airflow direction, on the side of the outlet, it is possible to improve heat exchange performance while suppressing frost.

(4-3)

The first heat exchange section 23 a and the second heat exchange section 23 b are integral with each other.

(5) Modification

With the first heat exchange section 23 a being disposed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator and the second heat exchange section 23 b being disposed on the outlet side, a third heat exchange section 23 c may be disposed between the first heat exchange section 23 a and the second heat exchange section 23 b.

In the third heat exchange section 23 c, the distribution center (i.e., center of distribution) of the flat pipes 231 in the width direction coincides with the center of the heat transfer fins 232 in the airflow direction.

The technical significance of this modification is that it is possible to try a combination of the heat exchange sections suitable for a refrigerant temperature in the outdoor heat exchanger 23 that functions as an evaporator. As a result, it is possible to improve heat exchange performance while suppressing frost.

The first heat exchange section 23 a may be integral with at least either one of the second heat exchange section 23 b and the third heat exchange section 23 c.

Second Embodiments

In one or more embodiments, a stack-type heat exchanger in which the flat pipes 231 are inserted into the cutouts 232 c provided in the heat transfer fins 232 is employed as the outdoor heat exchanger 23.

In one or more embodiments, a stack-type heat exchanger in which flat pipes extend through elongated holes provided in heat transfer fins is employed as the outdoor heat exchanger 23.

(1) Suppression of Frost

FIG. 7A is a perspective view of a first heat exchange section 123 a of the outdoor heat exchanger 23 according to one or more embodiments. In the first heat exchange section 123 a in FIG. 7A, a distance from the windward-side end of a flat pipe 231M positioned on the most windward side in the airflow direction to the windward-side end of a heat transfer fin 232M is a first dimension D1.

FIG. 7B is a perspective view of a second heat exchange section 123 b of the outdoor heat exchanger 23 according to embodiments. In the second heat exchange section 123 b in FIG. 7B, a distance from the windward-side end of the flat pipe 231M positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232M is a second dimension D2 smaller than the first dimension D1.

Since the distance (second dimension D2) from the windward-side end of the flat pipe 231M positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232M in the second heat exchange section 123 b illustrated in FIG. 7B is smaller than the distance (first dimension D1) in the first heat exchange section 123 a, a difference between an air temperature and a heat-exchanger surface temperature is large. The second heat exchange section 123 b thus has a feature of improving heat exchange performance but easily causing frost.

Meanwhile, since the distance from the windward-side end of the flat pipe 231M positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232M in the first heat exchange section 123 a illustrated in FIG. 7A is larger than the distance (second dimension D2) in the second heat exchange section 123 b, a difference between an air temperature and a heat-exchanger surface temperature is small, compared with the second heat exchange section 123 b, which suppresses frost.

Therefore, in one or more embodiments, the first heat exchange section 123 a is formed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator.

(2) Improvement of Heat Exchange Performance

As described above, compared with the second heat exchange section 123 b, a difference between an air temperature and a heat-exchanger surface temperature is small in the first heat exchange section 123 a. The heat exchange performance is thus degraded. Therefore, constituting the entirety of the outdoor heat exchanger 23 by the first heat exchange section 123 a may not be preferable for performance.

Thus, in one or more embodiments, both the first heat exchange section 123 a and the second heat exchange section 123 b are used, as in the first embodiments, to improve heat exchange performance while suppressing frost. FIG. 6A and FIG. 6B are also applied to the second embodiments by replacing the first heat exchange section 23 a of the first embodiments with the “first heat exchange section 123 a” and replacing the second heat exchange section 23 b of the first embodiments with the “second heat exchange section 123 b”.

In FIG. 6A, when the outdoor heat exchanger 23 functions as an evaporator for the refrigerant, the refrigerant that has flowed into the first header 233 a is distributed to the internal flow paths of the flat pipes of the stages substantially evenly and flows toward the second header 233 b. The temperature of the non-azeotropic refrigerant mixture at the evaporator inlet easily decreases, which easily causes frost. Therefore, a certain section from the first header 233 a toward the second header 233 b is constituted by the first heat exchange section 123 a to suppress frost.

Meanwhile, the temperature of the non-azeotropic refrigerant mixture increases toward the evaporator outlet. Thus, to improve heat exchange performance, a part between the first heat exchange section 123 a and the second header 233 b is constituted by the second heat exchange section 123 b.

It is possible by thus disposing the first heat exchange section 123 a on the evaporator inlet side and the second heat exchange section 123 b on the evaporator outlet side to improve heat exchange performance while suppressing frost.

(3) Features of Second Embodiments

(3-1)

The temperature of the non-azeotropic refrigerant mixture increases from the inlet toward the outlet of the evaporator. Thus, a high priority on frost proof performance (capacity of suppressing frost) on the inlet side and a high priority on heat exchange performance on the outlet side may be put.

Therefore, it is possible to try a combination suitable for a refrigerant temperature in the evaporator, the combination being such that the first heat exchange section 123 a is disposed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator and the second heat exchange section 123 b is disposed on the outlet side.

(3-2)

The first heat exchange section 123 a and the second heat exchange section 123 b are integral with each other.

(4) Modification

With the first heat exchange section 123 a being disposed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator and the second heat exchange section 123 b being disposed on the outlet side, a third heat exchange section may be disposed between the first heat exchange section 123 a and the second heat exchange section 123 b.

FIG. 7C is a perspective view of a third heat exchange section 123 c of the outdoor heat exchanger 23 according to a modification of one or more embodiments. In the third heat exchange section 123 c in FIG. 7C, a distance (a first distance) D3 from the windward-side end of the flat pipe 231M positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232M and a distance (a second distance) from the leeward-side end of the flat pipe 231M positioned on the most leeward side in the airflow direction to the leeward-side end of the heat transfer fin 232M are equal to each other.

The technical significance of this modification is that it is possible to try a combination of the heat exchange sections suitable for a refrigerant temperature in the outdoor heat exchanger 23 that functions as an evaporator. As a result, it is possible to improve heat exchange performance while suppressing frost.

The first heat exchange section 123 a may be integral with at least either one of the second heat exchange section 123 b and the third heat exchange section 123 c.

Third Embodiments

In the first embodiments and the second embodiments, a stack-type heat exchanger is employed as the outdoor heat exchanger 23. In one or more embodiments, a cross-fin-type heat exchanger is employed as the outdoor heat exchanger 23.

(1) Suppression of Frost

FIG. 8A is a perspective view of a first heat exchange section 223 a of the outdoor heat exchanger 23 according to one or more embodiments. In the first heat exchange section 223 a in FIG. 8A, when a plurality of heat transfer tubes 231N are viewed as a heat-transfer-tube group in the plate thickness direction of a heat transfer fin 232N, the distribution center of the heat-transfer-tube group in the airflow direction is positioned on the leeward side of the center of the heat transfer fin 232N in the airflow direction.

FIG. 8B is a perspective view of a second heat exchange section 223 b of the outdoor heat exchanger 23 according to one or more embodiments. In the second heat exchange section 223 b in FIG. 8B, the distribution center of the heat-transfer-tube group in the airflow direction is positioned on the windward side of the center of the heat transfer fin 232N in the airflow direction.

Since the distribution center of the heat-transfer-tube group is positioned on the windward side of the center of the heat transfer fin 232N in the airflow direction, a distance from the windward-side end of the heat transfer tube 231N positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232N is smaller in the second heat exchange section 223 b illustrated in FIG. 8B than the distance in the first heat exchange section 223 a. As a result, a difference between an air temperature and a heat-exchanger surface temperature is large. The second heat exchange section 223 b thus has a feature of improving heat exchange performance but easily causing frost.

Meanwhile, since the distribution center of the heat-transfer-tube group in the airflow direction is positioned on the leeward side of the center of the heat transfer fin 232N in the airflow direction, a distance from the windward-side end of the heat transfer tube 231N positioned on the most windward side in the airflow direction to the windward-side end of the heat transfer fin 232N is larger in the first heat exchange section 223 a illustrated in FIG. 8A than the distance in the second heat exchange section 223 b. As a result, compared with the second heat exchange section 223 b, a difference between an air temperature and a heat-exchanger surface temperature is small, which suppresses frost.

Therefore, in one or more embodiments, the first heat exchange section 223 a is formed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator.

(2) Improvement of Heat Exchange Performance

As described above, compared with the second heat exchange section 223 b, a difference between an air temperature and a heat-exchanger surface temperature is small in the first heat exchange section 223 a. The heat exchange performance is thus degraded. Therefore, constituting the entirety of the outdoor heat exchanger 23 by the first heat exchange section 223 a may not be preferable for performance.

Thus, in one or more embodiments, both the first heat exchange section 223 a and the second heat exchange section 223 b are used, as in the first embodiments and the second embodiments, to improve heat exchange performance while suppressing frost. FIG. 6A and FIG. 6B are also applied to the third embodiments by replacing the first heat exchange section 23 a of the first embodiments with the “first heat exchange section 223 a” and replacing the second heat exchange section 23 b of the first embodiments with the “second heat exchange section 223 b”.

In FIG. 6A, when the outdoor heat exchanger 23 functions as an evaporator for the refrigerant, the refrigerant that has flowed into the first header 233 a is distributed to the heat transfer tubes of the stages substantially evenly and flows toward the second header 233 b. The temperature of the non-azeotropic refrigerant mixture at the evaporator inlet easily decreases, which easily causes frost. Therefore, a certain section from the first header 233 a toward the second header 233 b is constituted by the first heat exchange section 223 a to suppress frost.

Meanwhile, the temperature of the non-azeotropic refrigerant mixture increases toward the evaporator outlet. Thus, to improve heat exchange performance, a part between the first heat exchange section 223 a and the second header 233 b is constituted by the second heat exchange section 223 b.

It is possible by thus disposing the first heat exchange section 223 a on the evaporator inlet side and the second heat exchange section 223 b on the evaporator outlet side to improve heat exchange performance while suppressing frost.

(3) Features of Third Embodiments

(3-1)

The temperature of the non-azeotropic refrigerant mixture increases from the inlet toward the outlet of the evaporator. Thus, a high priority on frost proof performance (capacity of suppressing frost) on the inlet side and a high priority on heat exchange performance on the outlet side may be put.

Therefore, it is possible to try a combination suitable for a refrigerant temperature in the evaporator, the combination being such that the first heat exchange section 223 a is disposed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator and the second heat exchange section 223 b is disposed on the outlet side.

(3-2)

The first heat exchange section 223 a and the second heat exchange section 223 b are integral with each other.

(4) Modification

With the first heat exchange section 223 a being disposed on the inlet side of the outdoor heat exchanger 23 that functions as an evaporator and the second heat exchange section 223 b being disposed on the outlet side, a third heat exchange section may be disposed between the first heat exchange section 223 a and the second heat exchange section 223 b.

FIG. 8C is a perspective view of a third heat exchange section 223 c of the outdoor heat exchanger 23 according to a modification of one or more embodiments. In the third heat exchange section 223 c in FIG. 8C, the distribution center of the heat-transfer-tube group in the airflow direction coincides with the center of the fin in the airflow direction.

The technical significance of this modification is that it is possible to try a combination of the heat exchange sections suitable for a refrigerant temperature in the outdoor heat exchanger 23 that functions as an evaporator. As a result, it is possible to improve heat exchange performance while suppressing frost.

The first heat exchange section 223 a may be integral with at least either one of the second heat exchange section 223 b and the third heat exchange section 223 c.

<Others>

In each of the embodiments described above, the non-azeotropic refrigerant mixture is described to include any of a HFC refrigerant, a HFO refrigerant, CF3I, and a natural refrigerant. More specifically, a non-azeotropic refrigerant mixture corresponding to any of (A) to (G) below may be used.

(A)

A non-azeotropic refrigerant mixture that includes any of R32, R1132(E), R1234yf, R1234ze, CF3I, and CO2

(B)

A non-azeotropic refrigerant mixture that includes at least R1132(E), R32, and R1234yf

(C)

A non-azeotropic refrigerant mixture that includes at least R1132(E), R1123, and R1234yf

(D)

A non-azeotropic refrigerant mixture that includes at least R1132(E) and R1234yf

(E)

A non-azeotropic refrigerant mixture that includes at least R32, R1234yf, and at least one of R1132a and R1114

(F)

A non-azeotropic refrigerant mixture that includes at least R32, CO2, R125, R134a, and R1234yf

(G)

A non-azeotropic refrigerant mixture that includes at least R1132(Z) and R1234yf

Embodiments of the present disclosure have been described above; however, it should be understood that various changes in the forms and details are possible without departing from the gist and the scope of the present disclosure described in the claims.

The present disclosure is widely applicable to a refrigeration apparatus capable of performing cooling operation and heating operation.

Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present disclosure. Accordingly, the scope of the disclosure should be limited only by the attached claims.

REFERENCES SIGNS LIST

-   -   1 air conditioning apparatus (refrigeration apparatus)     -   23 outdoor heat exchanger (evaporator)     -   23 a first heat exchange section     -   23 b second heat exchange section     -   23 c third heat exchange section     -   123 a first heat exchange section     -   123 b second heat exchange section     -   123 c third heat exchange section     -   223 a first heat exchange section     -   223 b second heat exchange section     -   223 c third heat exchange section     -   231 flat pipe (heat transfer tube)     -   231M flat pipe (heat transfer tube)     -   231N heat transfer tube     -   232 heat transfer fin     -   232 c cutout     -   232M heat transfer fin     -   232N heat transfer fin

PATENT LITERATURE

-   PTL 1 -   WO2017/183180 

What is claimed is:
 1. An evaporator comprising: fins disposed at a predetermined interval in a fin thickness direction; heat transfer tubes extending through the fins in the fin thickness direction; and a first heat exchange section in which, when the heat transfer tubes are viewed in the fin thickness direction, a center of distribution of the heat transfer tubes in an airflow direction is on a leeward side of a center of the fins in the airflow direction, wherein the evaporator is disposed in a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed.
 2. The evaporator according to claim 1, further comprising a second heat exchange section in which the center of the distribution of the heat transfer tubes is on a windward side of the center of the fins in the airflow direction when the heat transfer tubes are viewed in the fin thickness direction.
 3. The evaporator according to claim 2, further comprising a third heat exchange section in which the center of the distribution of the heat transfer tubes coincides with the center of the fins in the airflow direction when the heat transfer tubes are viewed in the fin thickness direction.
 4. The evaporator according to claim 2, wherein the first heat exchange section is integral with the second heat exchange section.
 5. The evaporator according to claim 3, wherein the first heat exchange section is integral with one or more of the second heat exchange section and the third heat exchange section.
 6. An evaporator comprising: fins disposed at a predetermined interval in a fin thickness direction; heat transfer tubes extending through the fins in the fin thickness direction; a first heat exchange section in which a distance from a windward-side end of one of the heat transfer tubes disposed on a most windward side in an airflow direction to a windward-side end of the fins is a first dimension; and a second heat exchange section in which a distance from a windward-side end of one of the heat transfer tubes disposed on a most windward side in the airflow direction to a windward-side end of the fins is a second dimension smaller than the first dimension, wherein, the evaporator is disposed in a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed.
 7. The evaporator according to claim 6, further comprising a third heat exchange section in which a first distance is equal to a second distance, wherein, the first distance is from a windward-side end of one of the heat transfer tubes disposed on a most windward side in the airflow direction to a windward-side end of the fins, and the second distance is from a leeward-side end of one of the heat transfer tubes disposed on a most leeward side in the airflow direction to a leeward-side end of the fins.
 8. The evaporator according to claim 6, wherein the first heat exchange section is integral with the second heat exchange section.
 9. The evaporator according to claim 7, wherein the first heat exchange section is integral with one or more of the second heat exchange section and the third heat exchange section.
 10. An evaporator comprising: fins disposed at a predetermined interval in a fin thickness direction; and heat transfer tubes extending through the fins in the fin thickness direction, wherein each of the fins has cutouts that are in a direction orthogonal to an airflow direction and the fin thickness direction, the heat transfer tubes are flat multi-hole pipes inserted into the cutouts, the evaporator comprises a first heat exchange section in which an opening side of the cutouts is on a leeward side in the airflow direction, and the evaporator is disposed in a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture is enclosed.
 11. The evaporator according to claim 10, further comprising a second heat exchange section in which the opening side of the cutouts is disposed on a windward side in the airflow direction.
 12. The evaporator according to claim 11, wherein the first heat exchange section is integral with the second heat exchange section.
 13. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes any of an HFC (hydrofluorocarbon) refrigerant, an HFO (hydrofluoroolefin) refrigerant, CF3I (trifluoroiodomethane), and a natural refrigerant.
 14. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes any of R32, R1132(E), R1234yf, R1234ze, CF3I, and CO2.
 15. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R1132(E), R32, and R1234yf.
 16. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R1132(E), R1123, and R1234yf.
 17. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R1132(E) and R1234yf.
 18. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R32, R1234yf, and at least one of R1132a or R1114.
 19. A refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R32, CO2, R125, R134a, and R1234yf.
 20. The refrigeration cycle apparatus comprising: the evaporator according to claim 1, wherein the non-azeotropic refrigerant mixture includes at least R1132(Z) and R1234yf. 